BCGControlBar Pro for MFC
UINT BCGM_ON_ACTIVATE_MDI_TEAR_OFF_FRAME

The BCGM_ON_ACTIVATE_MDI_TEAR_OFF_FRAME message is sent to the main application window when a tear-off MDI frame window is activated or deactivated.

Parameters
wParamif this parameter is not zero, MDI frame is active; zero - inactive.
lParama pointer to CBCGPMDIFrameWnd object.
Returns
the return value is ignored.